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gpio: support threaded interrupts in irqchip helpers

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Some off-chip GPIO expanders need to be communicated by I2C or
SPI traffic, but may still support IRQs. By the sleeping nature
of such buses, such IRQ handlers need to be threaded. Support
such handlers in the gpiochip irqchip helpers by flagging IRQs
as threaded if the .can_sleep property of the gpiochip is
true.

Helpfully deny registration of chained IRQ handlers if the
.can_sleep property is set, as such chips will invariably need
a nested handler rather than a chained handler.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Linus Walleij 2014-04-09 13:34:39 +02:00
parent d1db0eea85
commit 1c8732bb03
2 changed files with 16 additions and 1 deletions
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5
include/linux/gpio/driver.h
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@ -51,7 +51,10 @@ struct seq_file;
* format specifier for an unsigned int. It is substituted by the actual
* number of the gpio.
* @can_sleep: flag must be set iff get()/set() methods sleep, as they
* must while accessing GPIO expander chips over I2C or SPI
* must while accessing GPIO expander chips over I2C or SPI. This
* implies that if the chip supports IRQs, these IRQs need to be threaded
* as the chip access may sleep when e.g. reading out the IRQ status
* registers.
* @exported: flags if the gpiochip is exported for use from sysfs. Private.
*
* A gpio_chip can help platforms abstract various sources of GPIOs so